Cellular wireless communications systems, for example, are designed to serve multiple wireless-enabled devices distributed over a large geographic area by dividing the area into regions called “cells” or “cell areas”. At or near the center of each cell area, a network-side access device (e.g., an access point or base station) is located to serve client devices located in the cell area and commonly referred to as “access terminals” (“ATs”) or user equipment (“UEs”). Examples of ATs or UEs include wireless-enabled devices such as cellular telephones, laptops, personal digital assistants (PDAs), and/or other user equipment (e.g., mobile devices). An access terminal generally establishes a call, also referred to as a “communication session,” with an access point to communicate with other entities (e.g., servers) in the network.
Mobile wireless cellular networks (e.g. UMTS/WCDMA) have been implemented and are in operation globally. However, the coverage of those 2G/3G macro networks is often poor which causes call disruption to customers at home and inside buildings. The home base station (sometimes referred to as Home NodeB (“HNB”) or Femtocell Access Points “FAP”) is a solution to the indoor coverage problem providing complementary indoor coverage to 2G/3G macro networks for service continuity; moreover, it also acts as a new service platform to enable mobile wireless broadband applications and home entertainment.
A common problem in a lightly coordinated cellular network (e.g., a macro-Femto mixed network) is that cells do not have sufficient and accurate knowledge about their neighbors. So, ambiguity is created in (target) cell identification for a UE in active mode which can disrupt activities such as hand-over towards FAPs. For example, such identification ambiguity may cause inaccuracy and excessive failures in hand-over attempts for a UE in active mode.
Various proposals have been made concerning methods for hand-overs into Femto networks. The proposals include a method for identifying the hand-over target by using the Primary Scrambling Code (PSC), and a method for identifying the hand-over target by identifying an umbrella macro cell. However, many of these proposals are based on shared and ambiguous target identifiers and consequently still cause excessive hand-over failure and unwanted signaling. For instance, in some conventional systems, hundreds of simultaneous hand-ins are attempted in hopes of getting correctly identifying the desired target cell. This approach unnecessarily wastes network resources.